will walmart cash a check after its 6 months old?

It is unlikely that Walmart will cash a check that is six months past its issue date. You can call their check cashing hotline 1-479-204-2125 and find out. It might depend on what type of check and who it is from. It is probable that you will have to contact the issuer and get a new check - but find out first.

Although there is no firm rule about this, most banks will not cash a check that is more than 6 months old. The only exception I know of is tax return checks - right on the check it says "valid for one year" and I've cashed them when they were 8 to 10 months old.

I don't know Walmart's policy on 6-month-old checks, but in my experience, stores are usually more stringent than banks about cashing checks.